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What Size Tankless Water Heater Do I Need?

When it comes to choosing a water heater, tankless systems are the first choice of homeowners around the world. From superior energy efficiency to compact design, there are numerous benefits of tankless water heaters.

The importance of choosing the right-sized water heater for your home cannot be emphasized enough. If you choose a water heater that’s too small, you won’t get enough hot water. An oversized heater, on the other hand, will draw too much power, negating one of the most significant benefits of tankless water heaters – energy efficiency.

Here are some factors to consider when determining the size of the water heater that you need.

Water Flow Rates

The efficiency of your tankless water heater is determined by the water flow rates inside your home.

Your heater must be able to provide the right flow rate to meet your needs. Some efficient, low-flow hot water plumbing features are – showerheads (2.5 GPM), tub faucets (4 GPM), dishwashers (1.5 GPM), bathroom sink faucets (1 GPM), and washing machines (2 GPM).

Determine how many of these fixtures you expect to use during peak times. If, for instance, you have two bathrooms and determine that two people would want to shower at the same time every morning, you need a water flow rate of 5 GPM.

Required Temperature Rise

Find the temperature of the water when it goes in and comes out. This is known as temperature rise. To calculate temperature rise, subtract the temperature of the water when it goes in from your desired output temperature.

An example

Suppose the incoming water temperature in your home is 50 degrees Fahrenheit. Let’s assume, you want your water heated to 105 degrees Fahrenheit. Look for a tankless water heater that can produce a temperature rise of 55 degrees (105 – 50 = 55) Fahrenheit.

Putting It All Together

Now that you know your hot water demand and the required temperature rise, look for a heater that meets your requirements. Remember to refer to sizing charts provided by manufacturers.

A sizing chart usually specifies the product’s maximum flow rates at different temperatures. Some manufacturers provide more detailed information such as flow rates for different input and output water temperature.

Watch out for misleading information. If you are confused, consult your plumber when buying a water heater in Santa Rosa.

Need help choosing the right water heater for your home? Look no further than Holman Plumbing. We know a thing or two about water heaters. As one of the most trusted plumbers in Santa Rosa, we are committed to helping families make informed decisions regarding their plumbing systems. To discuss your requirements with one of our experts, call us at 707-495-5002.

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